  #ifndef LOG_H
  #define LOG_H

  #include <stdio.h>
  #include <stdarg.h>
  #include <stdbool.h>
  #include <time.h>

  #define LOG_VERSION "0.1.0"

  typedef struct {
      va_list ap;
      const char *fmt;
      const char *file;
      struct tm *time;
      void *udata;
      int line;
      int level;
  } log_Event;

  typedef void (*log_LogFn)(log_Event *ev);
  typedef void (*log_LockFn)(bool lock, void *udata);

  enum { LOG_TRACE, LOG_DEBUG, LOG_INFO, LOG_WARN, LOG_ERROR, LOG_FATAL };

  #define log_trace(...) log_log(LOG_TRACE, __FILE__, __LINE__, __VA_ARGS__)
  #define log_debug(...) log_log(LOG_DEBUG, __FILE__, __LINE__, __VA_ARGS__)
  #define log_info(...)  log_log(LOG_INFO,  __FILE__, __LINE__, __VA_ARGS__)
  #define log_warn(...)  log_log(LOG_WARN,  __FILE__, __LINE__, __VA_ARGS__)
  #define log_error(...) log_log(LOG_ERROR, __FILE__, __LINE__, __VA_ARGS__)
  #define log_fatal(...) log_log(LOG_FATAL, __FILE__, __LINE__, __VA_ARGS__)

  const char* log_level_string(int level);
  void log_set_lock(log_LockFn fn, void *udata);
  void log_set_level(int level);
  void log_set_quiet(bool enable);
  int log_add_callback(log_LogFn fn, void *udata, int level);
  int log_add_fp(FILE *fp, int level);

  void log_log(int level, const char *file, int line, const char *fmt, ...);

  #endif
